Now the Kenda 26ers are mounted to Sun Doubletrack rims, so they're getting maximum rim width advantage to their widths and volumes possible. The 650B tires are both mounted to Weinmann Discovery rims which are very much at the wider stage of what most of us use for trail riding... they're wider than Blunts for example. The Karma is on a typical 24mm width XC type rim and the 26er RaRa is on a 26mm width XC rim.

I don't post to generate business for myself or make like I'm better than sliced bread

And despite all that effort, they'll be many who will still stick to their case, since they can argue rim differences, tire and wear differences, photo taking procedure, how level the ground and background is, etc and how those can lead to misleading info.

Not to be the Devil's Advocate, but that second picture isn't very convincing, and neither are your measurements. The far left 650b tire is not much taller than the biggest 26" tire (Nevegal 2.35"), and according to your measurements, there's only a 1/2" between them. That's supposed to convince someone that it's significantly different? A half inch of wheel diameter- when it's really supposed to be closer to 1.5" - is a pretty poor argument.

Out of curiosity, I went out and measured the 26" wheel on my NomadC (2.5" Maxxis Minion DHF on Easton Haven wheels) and found them to be right around 26.8". I'm not arguing for or against 650B tires/wheels since I haven't ridden a bike with them, but I'm not sure your argument is all that strong. I was expecting to see a bigger difference, personally.

Not to be the Devil's Advocate, but that second picture isn't very convincing, and neither are your measurements. The far left 650b tire is not much taller than the biggest 26" tire (Nevegal 2.35"), and according to your measurements, there's only a 1/2" between them. That's supposed to convince someone that it's significantly different? A half inch of wheel diameter- when it's really supposed to be closer to 1.5" - is a pretty poor argument.

Actually it was never supposed to be 1.5" bigger in anything but name, hence the stupidity of some brands/people calling them 27.5ers... Most 26" labeled tires are NOT in fact, exactly 26" diameter. I thought about including a 26 x 1.5 in the photo series to show how much smaller diameter than 26" that tire is. I could also put in a 26 x 1.0 as I have some and they're 24.25" diameter. Tire diameters grow with tire widths, and the original 26" tires were named that by rounding down to the nearest whole number. Likewise referring to 650B mountain tires as 27.5 came from rounding down to the nearest tenth of an inch.

Out of curiosity, I went out and measured the 26" wheel on my NomadC (2.5" Maxxis Minion DHF on Easton Haven wheels) and found them to be right around 26.8". I'm not arguing for or against 650B tires/wheels since I haven't ridden a bike with them, but I'm not sure your argument is all that strong. I was expecting to see a bigger difference, personally.

Why? Did it never occur to you that a 26 x 2.5 was bigger than 26" diameter? Have you never looked at the tires of a DH bike next to an XC bike around a group ride?

I could have added in one of my 26 x 3.8 wheels from my mukluk to the photo as well. There's more than just rim diameters as play in inflated tire diameters... you have the casing size, and the amount of tread on them also. The nevegal has tread blocks twice as deep/tall as the Racing Ralphs or Karmas. I have a Panaracer Rampage 29 x 2.35 I could put into a photo as well, along with a Schwalbe RaRa 29 x 2.4. If I had one of the Surly 29 x 3.0's to photograph I'd do that one also. They're supposedly close to 31 inches in actual diameter.

I don't post to generate business for myself or make like I'm better than sliced bread

There's also the issue with rims. A tire only measures so much across, measuring bead to bead. Most mfgs believe a width of about 20mm is ideal, being the best compromise for tire shape/profile and rim weight, for the most common sized mtb tires. You can see how a tire's height is lower with wider rims with this illustration. Despite all the rage with wide rims these days, a good number of pro DHers still race on 21mm internal width rims (ex. Mavic DeeMax), at the one of the highest levels of the sport, pounding them at max speed over technical sections.

26" mtb wheels and tires using a 2.1 to 2.25 tire, are closer to 26.5" and not 26"... convert the tire heights from this familiar graphic, or measure your own 2.1 tires. A 650B wheel with a 2.25" tire is about 27.5". The bottom line is the rims in 26" and 650B are essentially exactly 1 inch different in height. Add tires and compare apples to apples. Anyways, all that matters is anybody questioning the difference be willing to try 650B wheels/tires with an open mind.

It's not supposed to be an accurate representation. It's just simplified to give an idea of how the height of a tire's carcass is compromised when the beads are mounted wider, assuming the BSD is constant and the carcass inflates to a perfectly rounded shape. Applicable here, since people are talking about diameters of different tires on different rims. It's only misleading if you try to use the image to try and come with other conclusions that it wasn't intended to support.

Yes, but the widest rim available today - the P35 - will still be narrower than the point "1" on your X axis. Basically for all rims available today the rule is simple - the wider the rim, the taller the tire. The extremely wide rims that would make the tire less tall do not exist.

Yes, rim width will influence the shape of the tire. In another thread posted here, I offered a comparison of a Noby Nic 2.25 on a 19mm wide rim and a 30mm wide rim - the height and roundness differs by several millimeters. But, the differences are not as drastic as your image is suggesting. Tires and rims available today will all fit between the two extremes of 0.5 and 1.0 in your chart. Everything else in the picture is noise. I understand your good intentions but you also said "notice how tire height is lower with wider rims" which is simply an incorrect statement because the rims would have to be wider than 2.5".

Yes, rim width will influence the shape of the tire. In another thread posted here, I offered a comparison of a Noby Nic 2.25 on a 19mm wide rim and a 30mm wide rim - the height and roundness differs by several millimeters. But, the differences are not as drastic as your image is suggesting. Tires and rims available today will all fit between the two extremes of 0.5 and 1.0 in your chart. Everything else in the picture is noise. I understand your good intentions but you also said "notice how tire height is lower with wider rims" which is simply an incorrect statement because the rims would have to be wider than 2.5".

You know you are almost like the type of guy the OP is targeting, except this case deals with rim width vs tire profile. I say you're almost like that type, since you outright deny something with evidence backing it up, without convincing evidence of your own, yet the guy the OP profiled isn't exactly wrong, as a 0.5" to 1" diameter difference might be considered almost the same size or not that much bigger to some, notably when comparing to the difference between 26 and 29er.

Since you are so smart and have a patent to call others whiners, why do not you show us where a 25mm wide rim would be in your chart, and then a 20mm and a 30mm ones? And then show how the 30mm one would result in a less tall tire than the 20mm one? That's why you brought the chart to this discussion in the first place, no? Stop blabbering and show me the money.

Kirk Pacenti when trying to explain WHY make 650B tires was probably who first tried to say they're about 27.5" in diameter to sell them as a in-between option from 26er to 29er. He probably assumed anyone listening/reading what he said would have had the common sense to know that the majority of 26er tires aren't exactly 26" in practice, nor are the majority of 29er tires exactly 29" either. In that assumption, he was very wrong. He should have anticipated dealing with morons in giving his response on how big they are.

On an early-90s hybrid I converted for my now ex-gf, into a more off-road capable bike, I took advantage of the available frame & fork clearance to fit the widest tires I could. They were bontrager jones XR foldables labeled as 29 x 1.8. Now in practice, inflated diameters were more like 28.3-28.4" as while they were 1.8s in tread width, they were only 1.6 in casing width. If NOT for the 29er movement, we'd still have been calling those tires as 28ers or 700x45Cs. For my current gf, I built up a Niner Air9 with Schwalbe RaRa tires, originally 2.4s front and back on an Easton XC wheelset but when I built her new wheels using Stan's Crest rims, the profile on the tires changed and the back tire grew in inflated width enough to rub the stays and I had to switch to a 2.25 in back.

On my first personal 29er, a GT Peace 9R multi, it originally came with WTB Weirwolf 2.3 wirebeads on WTB SpeedDisc AM rims. When trying to diet it a year ago, I put on the silver wheelset (of which the karma in my photos is mounted to) with Panaracer Rampage 2.35 foldables and those fit fine also. This spring I built a new wheelset for it using Mavic Tn719 rims and the same tires and then the profile grew in width enough as to make the tire rub the inside of the front derailleur cage when I downshifted to the granny cog.

I am running Pacenti Quasi-Moto 2.0s on one bike and inflated I believe I measured them out as 27.1-27.2" diameter. But compared to those 26" x 2.35 Nevegals... they weigh HALF A POUND less per tire. Hell my NeoMoto 2.3s are the same weight as those Nevegals for a 15mm increase in diameter (and also of course, an increase in air volume which means I can run lower pressure and pickup even more traction to go along with the longer tire footprint).

Last edited by DeeEight; 12-06-2012 at 09:18 AM.

I don't post to generate business for myself or make like I'm better than sliced bread

i don't think showing the range of overall diameters with pictures like these is the best way to visually differentiate (potential) rolling performance, as only a percentage of the wheel circumference is engaged. i'm thinking a side profile shot of each wheel at the ground level would make better sense as you can see the relative differences of curvature and how they would (potentially) roll over surfaces differently.

I find this excerpt from Bicycling mag to be illustrative and explanatory of the whole Wheel size issue: rim size nude; wheel size with tire mounted on rim. Couldn't find a link, so I took a pic from the page in the mag

Old enough to know better. And old enough not to care. Best age to be.